This invention relates to devices for coupling pipes together, and more particularly, to the coupling of pressurized or non-pressurized piping so as to minimize rotation of one length of pipe relative to the adjacent length of pipe, while simultaneously preventing the pipes from separating.
Pipe junction restrainers and techniques for their assembly have been developed to make fluid-tight connections between two axially-aligned pipes, joints, valves, fittings, hydrants, or other types of fluid connections. Often, these junction restrainers must withstand extraordinarily great pressures associated with water distribution and sewer connections. Such devices may include, for example, segmented or split pipe joint retainer glands, which are well known and typically are secured together around a pipe section by ears or lugs formed on, or extending radially outwardly from, the gland segments.
It has been current practice to employ polyvinyl chloride (PVC) plastic pipe in new construction. One popular system employed for connecting PVC pipe, sold under the trademark CERTA-LOK(trademark) and produced by CertainTeed Corporation, Valley Forge, Pennsylvania, provides a rather unique restrained joint between a pair of pipe sections for municipal, fire protection and other uses. The joint connector uses a series of o-ring seals and internal annular cavities that are filled externally with polymeric dowels after two sections of PVC pipe are inserted into the connector. These dowels also fill matching annular cavities located on the pipe sections to form a restraining mechanical lock that can withstand considerable axial thrust. Since the restraining mechanism of the CERTA-LOK"ugr" joint connector is uniformly distributed around the PVC pipes, the risk of damaging the plastic sidewalls by localized stress fracture can be minimized.
It has been recently understood that the CERTA-LOK(trademark) system permits each of the axially-aligned plastic pipes to rotate relative to one another after they are joined together. These pipes are often subjected to torsion, such as when connected to a submersible electric pump, which creates torque throughout the piping system and may cause rotation of one or both pipes during the pumping of fluids. An excessive amount of rotation may cause damage due to abrasive wear on the outside of the pipe, or breakage to the electrical wires, and/or supporting cable for the pump.
One method of preventing the relative rotation of pipes coupled using a CERTA-LOK(trademark) pipe connection system has been to install set screws through the tubular fitting member surrounding the pipe. Although this method has some effect on reducing rotation, the effect is often of limited value.
Mechanical pipe connections are provided by this invention which include a tubular fitting member designed to receive the ends of a pair of fluid pipes. The first and second ends of the first and second of these pipes may optionally comprise a male coupler and a matching female coupler recess which can be interlocked after the pipes are inserted into the tubular fitting member to minimize rotation between the pipes. The coupler recesses of the pipes are uniquely structured, as will be explained below.
A prior invention (U.S. Pat. No. 5,868,443, herein incorporated by reference) provides an improved mechanical means for fitting a pair of pipes locked together with a CERTA-LOK(trademark)-type system so as to minimize thrust and rotation during pumping operations and the like. In the preferred embodiment of that invention, a portion of the ends of each pipe are extended about 0.5-1.5 inches or so past the center line of the tubular fitting member to occupy non-extended space at the end of an opposing pipe. Rotation of either pipe will cause the extended approximately one-half circumference of the first pipe to come into contact with the extended approximately one-half circumference of the opposing pipe of that embodiment. This contact inhibits the rotation of one pipe relative to the other pipe without the need for set screws. Of course, it is apparent that less than one-half of the circumference of each pipe is sufficient, so long as there is locking contact between a male coupling portion located on one pipe and the female coupling recess located on the other.
In the prior invention, a mechanical pipe connection was provided which included a tubular fitting member having a pair of open ends for receiving a pair of pipe end portions. The fitting member included an annular locking means for locking the fitting member to each of the pipe portions once they have been inserted. The first of the pipe end portions included a male coupler extending therefrom, and a second of the pipe end portions included a female coupler recess for receiving the male coupler in locking arrangement within the tubular fitting. This locking arrangement minimizes the degree to which the first and second pipe end portions can rotate relative to one another.
In a preferred embodiment of the present invention, the first and second pipes include a first pair of coupler recesses with discontinuous locking grooves; the tubular fitting member comprises a pair of second coupler recesses which can be interlocked with the first pair of coupler recesses of the first and second pipes for minimizing separation and rotation of the first and second pipes relative to one another.